If the up arrow on the scroll bar is visible, but the down arrow is not, you may need to display the Status Bar. In the View menu, click to put a check mark by Status Bar. The down arrow should reappear.

Thanks Joe,I got the Gmail arrow back.Have another problem now. On Firefox my bookmarks & history are not at the top where they were. They aren't anywhere. Had to get on Chrome to get here.
Could all this be indicative of a bug,virus,etc.?
Rose